It is particularly associated with Georgian-style and Colonial Revival houses:

Sorry, I'm confused....how does dentil replace exposed rafters???

You did not ask about the roof generally, but I would suggest varying the pitch on the front facing gables from that of the hips on the main roof. Secondary roofs usually look better at a slightly shallower pitch from the main roof. It is less "static" than having it all paralleled.

Also, the eave returns should have a shallower pitch. (All, at least according to classical architecture.)

I think, overall, the appearance of exposed rafter tails would be more suitable than the dentil moulding on your house. Dentil moulding is a rather formal detail.

Just for reference, these are the finishes in terms of color we have chosen. I'm aware that dentil molding is quite different than exposed rafters, but we are looking to add some more detail to the trim work of the house, and didn't know which one better fit our house's style? Would doing some form of brackets work better than any other option? We also plan to have much wider trim and facia than what is in the drawing. palimpsest- do you have any photo references for me of the eave returns and such that you mentioned? How do exposed rafter tails hold up in terms of maintenance and such? We really appreciate the feedback and advice! Thanks!

Is this type of accent considered dentil molding too, when it's so much wider?

The other issue in all of this is that we need to have gutters. Any knowledge about how that could also work? Thanks again!

Yes it is dentil moulding even at the wider spacing. That is a Georgian style house.

Brackets would be appropriate to your house.

Houses with dentil moulding of this sort traditionally have "yankee", "box", or integral gutters:

palimpsest- thank you so much for the photo references! Do you have any photos of specific brackets you could see us using on our house? I appreciate your time!

Actually the widely spaced brackets are modillions, which are ornamented brackets. I think this form is still too ornamental for your style of house because it is part of the Greek Orders

If you look at the Fypon catalogue, they sell a number of styles and sizes of Brackets that would be more suitable. Even if you have wood brackets built instead of using a material like Fypon, they would be worth looking at for ideas.

Thanks so much palimpsest! I think I agree with you about the formality of the modillions and dentil moldings. I'm going to definitely head to that website and do some looking into brackets. Do you have any suggestions with where you would put them- just in the peaks of the front gables, or is there anything we could incorporate into the front porch? Thanks again!